Method of forming sheet-metal elbows.



M. L. HUNKER.

' METHOD or FORMING SHEET MBTALELBOWS.

APPLIGATION FILED JULY 3, 1912.

Patented Apr. 8, 1913.

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1,058,590. Pat nted Apr. 8, 1913.

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UNITED STATES PATENT oFFIcE.

MARTIN L. BUNKER, or naeems FERRY, .OHIO, .AssIenon T0 WHEELING connoes'rme COMPANY, A conronamon :OF WEST VIRGINIA.

METHOD OF FORMING SHEET-METAL ELBOWS.

Specification-of Letters Patent Patented Apr. s, 1913.

Application filed July 8, 1912. 7 Serial No. 707,450.

Belmont, and State of Ohio, have invented certain new and useful Improvements in Methods of Forming Sheet-Metal Elbows, of which .the following is a specification.

This invention relates to amethod of producing sheet-metal elbows of the plaited type, and it has for an object to provide a process or method whereby such elbows may be readily manufactured at a. low cost.

A further object is to provide a simplemethod which admits of the employment of forming tools of relatively greater strength and which are more conveniently operated or handled than are those commonly employed in elbow manufacture. And a still further object-is to provide a method wherein the drawing out of portions of the plaits or folds provided in the sheetmetal blank is accomplished prior to forming the plaited blank into a tube.

WVith these and other objects in view, the invention consists in the process or method which will hereinafter be fully described, reference being had to the accompanying drawings, forming a part of this specification, in whic Figure l is a plan view of a sheet metal blank folded or plaited in a transverse, or crosswise, direction, illustrating the same as it appears at the completion of the first step .in the manufacture of an elbow; Fig. 2 is an edge view of the same; Fig. 3 is an end view of the same showing the lateral edges turned to form hooks; Fig. 4 is a similar view showing the plaited blank bent longitudinally into substantially U-shape; Fig. 5 is an inner face view of the same after portions of the plaits or folds have been drawn out to produce the proper degree of curvature and before joining of the edges; Fig. 6 is a side elevation of the completed elbow; Fig. 7 is a similar view of an elbow which is corrugated longitudinally; and Fig. 8 is a cross section on the line 8-8, Fig. 7.

Referring to said drawings, in which like designating characters distinguish like parts throughout the several views1 indicates a rectangular sheet-metal blank which is first doubled or folded transversely upon itself,

as shown in Figs. 1 and 2, to form a plurality of parallel folds or plaits-Q, the number of such plaits depending upon the angle desired for the elbow and 'upon the depth or width of the individual laits formed in the blank. The opposite L. eral edges of the blank are then turned over orbent in reverse directions, as shown in Fig. 3, to form continuous longitudinally-extending hooks 3, after which the blank is bent longitudinally into substantially U-'shape, or gutter-shape, as shown inFig. 4. Then, employing a machine designed for the purpose, the gutter-shaped blank is suitably gripped and is stretched longitudinally along a substantially median line to completely draw out those portions of the plaits along said line to produce a plain smooth surface, as shown-at 4 in Figs. 5, 6 and 7, while allowing the ends of the plaits to remain: undisturbed. This last-mentioned step, in the process accomplishes the curving of the article into bow-shape without stretchingor weakening the material, and leaves the article in substantially the. form illustrated in Fig. 5. The lateral edges are then drawn together and the hooks 3 placed in interlocking engagement throughout their lengths andpressed flat to form the usual seam.

I am aware that elbows have heretofore been produced by forming in a blank folds or plait-s portionsof which are later drawn out to produce the proper curvature, but in all such the blank is formed into a tube before the folds or plaits are drawn out, and the machinery required for accomplishing this stretching is, as a consequence, necessarily more or less complicated n its construction and lacks the strength requisite to withstand long-continued use. It will be noted that in my process the step of forming the tube follows t-hatof stretching or drawing out the plaits. Therefore, as will be apparent, mechanism employed for effecting the stretching may be relatively much simpler and stronger in its construction, and, consequently, less liable to become outof order. Furthermore, by my method it is possible to produce corrugated elbows practically as readily as plain elbows, the corruga-tions being formed before the blank is bent out of its plaited flat shape.

Having thus described, my invention,-

what I claim as new, Letters Patent, is

1. The method of manufacturing sheetand desire to secure by metal elbows, which consists, first, in forming plaits in a sheet-metal blank, then drawing out the plaits along a substantially median line While the ends of the plaits remain undisturbed, and finally uniting the lateral edges.

2. The method of manufacturing sheetmetal elbows, which consists, first, in forming plaits in a sheet-metal blank, bending the plaited blank into substantially U-shape, then drawing out the plaits along a sub-' stantially median line to produce the desired curvature, and finally uniting the lateral edges.

3. The method of manufacturing sheetmetal elbows, which consists, first, in forming transverse plaits in a sheet-metal blank, bending the plaited blank longitudinally into substantially U-shape, then drawing out the plaits along a substantially median line to produce the desired curvature, and

finally joining and seaming the lateral edges.

4. The method of forming plaited sheetmetal elbows, which consists, first, in forming plaits crosswise of a sheet-metal blank, corrugating the plaited blank longitudinally, bending the same into substantially U-shape, then drawing out the plaits along asubstantially median line to produce the desired curvature, and finally uniting the lateral edges.

5. The method of forming plaited sheetmetal elbows, which consists, first, in formblank to form reversely directed hooks,

bending 'theplaited blank into substantially U-shape, then drawing out said plaits along a substantially median line while the ends of the plaits remain undisturbed, and finally .drawing said hooks into interlocking cngagement.

In testimony whereof, I afiix my signature in presence of two subscribing witnesses.

MARTIN L. BUNKER. Witnesses:

H. E. DUNLAP, L. D. MORRIS. 

